Horton

Re: WAL usage calculation patch

Kyotaro Horiguchi <horikyota.ntt@gmail.com>

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From: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
To: rjuju123@gmail.com
Cc: pryzby@telsasoft.com, amit.kapila16@gmail.com, peter.eisentraut@2ndquadrant.com, dilipbalaut@gmail.com, kuntalghosh.2007@gmail.com, masao.fujii@oss.nttdata.com, kirill.bychik@gmail.com, pgsql-hackers@postgresql.org, thomas.munro@gmail.com
Date: 2020-04-20T07:46:56Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Change the display of WAL usage statistics in Explain.

  2. Cosmetic fixups for WAL usage work.

  3. Allow parallel create index to accumulate buffer usage stats.

  4. Allow autovacuum to log WAL usage statistics.

  5. Add the option to report WAL usage in EXPLAIN and auto_explain.

  6. Allow pg_stat_statements to track WAL usage statistics.

  7. Add infrastructure to track WAL usage.

  8. Include information on buffer usage during planning phase, in EXPLAIN output, take two.

  9. Include information on buffer usage during planning phase, in EXPLAIN output.

  10. Allow parallel vacuum to accumulate buffer usage.

  11. Allow pg_stat_statements to track planning statistics.

At Sun, 19 Apr 2020 16:22:26 +0200, Julien Rouhaud <rjuju123@gmail.com> wrote in 
> Hi Justin,
> 
> Thanks for the review!
> 
> On Sat, Apr 18, 2020 at 10:41 PM Justin Pryzby <pryzby@telsasoft.com> wrote:
> >
> > Should capitalize at least the non-text one ?  And maybe the text one for
> > consistency ?
> >
> > +               ExplainPropertyInteger("WAL fpw", NULL,
> 
> I think we should keep both version consistent, whether lower or upper
> case.  The uppercase version is probably more correct, but it's a
> little bit weird to have it being the only upper case label in all
> output, so I kept it lower case.

One space follwed by an acronym looks perfect.  I'd prefer capital
letters but small-letters also works well.

> > And add the acronym to the docs:
> >
> > $ git grep 'full page' '*/explain.sgml'
> > doc/src/sgml/ref/explain.sgml:      number of records, number of full page writes and amount of WAL bytes
> >
> > "..full page writes (FPW).."
> 
> Indeed!  Fixed (using lowercase to match current output).

I searched through the documentation and AFAICS most of occurances of
"full page" are follwed by "image" and full_page_writes is used only
as the parameter name.

I'm fine with fpw as the acronym, but "fpw means the number of full
page images" looks odd..

> > Should we also change vacuumlazy.c for consistency ?
> >
> > +                                                        _("WAL usage: %ld records, %ld full page writes, "
> > +                                                          UINT64_FORMAT " bytes"),
> 
> I don't think this one should be changed, vacuumlazy output is already
> entirely different, and is way more verbose so keeping it as is makes
> sense to me.

regards.

-- 
Kyotaro Horiguchi
NTT Open Source Software Center